By virtue of the increasing development of air travel, airports have grown considerably in size and aircraft parking areas are sometimes far removed from the point where an aircraft needs to be brought prior to a flight in order to allow passengers to board it. Further, it is out of the question to move an aircraft from its parking area to the boarding point using the aircraft's own propulsion means since that would require a pilot on board the aircraft which would make the maneuver too expensive. It is therefore common practice to use a tractor vehicle which is mechanically connected to an aircraft for towing it on the ground. When the tractor vehicle is connected to the aircraft by a tow bar which is generally connected to the aircraft's nose landing gear, the towing speed is very low, being about 4 kilometers per hour (km/h), thereby giving rise to a considerable loss of time. Proposals have also been made for using faster tractor vehicles having a platform onto which the nose landing gear of the aircraft is mounted.
In either case, the tractor-and-aircraft assembly is braked solely by a braking force applied to the tractor's wheels. This solution suffers both from the drawback of requiring a large tractor in order to ensure ground adherence when braking hard while towing a heavy aircraft, and from the drawback of applying considerable stress to the aircraft's nose landing gear since the braking force is transmitted from the tractor to the aircraft via the landing gear.
An aim of the present invention is to provide a system for braking an aircraft while it is being towed on the ground, which system enables the above drawbacks to be avoided while remaining reasonable in cost.